Frequency-indicator.



W. H. PRATT.

FREQUENCY INDICATOR.

APPLIOATION TILED SEPT. 19, 1911.

Patented Oct. 21, 1913.

v Inventor:

W/'///'am H. Pr'a 1171,-

' H/Lsflttorney,

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P-RLTT, 01 WEST LYNN, MASQACHBSETTS, ASSIGNQE 'JEO GENERAL BEECH-RIG COIBANY, A. CORPQRATIOIQ OF- NEW YORK.

newcomer-moraines.

s ecmcasonpatmrsrlama Patented Oct. 21, 1913 To all whom it may-concern: Be it known that I, WILLIAM a citizen of the United States, residing at West Lynn, county of Essex, State of Mas- --sachusetts, have invented certain new and rent circuits and its object is to provide an indicator which is highly sensitive over the small range of frequency variation; on

which such instruments are ordinarily required cooperate.

' 1 Obtain the desired result by providing one of the two relatively movable elements of the instrument with two windings exerting opposin forces on the other element and tuning e circuits of the two windings fortwo different frequencies above and below the average frequency to be indicated. For instance, if the average frequency of a circuit is sixty cycles, one winding may be tuned for $5 and the other for 55 cycles.

7 With such an adjustment, currents in the two windings at 69 cycles may be caused to produce balanced forces but a small variation in frequency above or below 60 cycles produce a rapid increase in the amount of current in one winding and a decrease in the current in the other winding, so that its! is shown in Fig. 2. In this modificathe opposing forces of the two windings will .be unbalanced by a large amount. -This meansthat wide deflections may be obtained with small variations in frequency or, in other words, that the instrument is highly sensitive. V h 7 .My intention will best be understoodby reference to the accomganying drawings in Figure l shows diagrammatically a frequency meter arranged in accordance with g my invention; Fig; 2 shows a modified form of the meter.

l'nFig. l, A. A represent two coils forming the stationary windin or a stationary element of the meter. B represent two windings constituting the movable element A of the instep which is pivotally mounted tuning the circuits to a given frequency. lhese devices are represented by reactances we and condensers b b'. The relative amount of reactance and capacity in the two parallel circuits is preferably adjustable as is indicated diagrammatically by the adjustable contacts in connection with the resistances. By means of these devices the circuits of windings ]B B" are tuned for different frequencies, the circuit of winding 3 being tuned for a higher frequency than that of winding B as is indicated by the smaller amount of reactance in the circuit of winding B. If the instrument is designed to operate on cycles asits average frequency, the circuit of winding B may be tuned for cycles and that of B for 55 cycles. Thus at 60- cycles currents in the two windings may be made approximately 1 equal but will differ by large amounts when the frequency varies two or three cycles Zeither side of 60. The windings B B are Q placed at an angle to each other and con- ;nected so as to exert opposing forces on the istationary coils A A. Thus at 60 cycles ithe coils exert balanced forces and the indiicator C carried by the movable clement occupies a central position. As the frequency grises or falls, one coil or the other exerts a predominating cfiect andthe indicator C 3 is moved in one direction or the other.

7 Another arrangement of a frequency ineition, the movable element D comprises sim- Eply a bar of iron while the stationary elecally displaced from each other and exert Emcnt comprises two coils E E mcchaniging o iposing forces on the armature D. The f ;circu1ts of these windings E E are tuned ifw difi'erent frequencies "in the same way ithat the windings B B are tuned .in the arrangement of Fig. l. I do not desire to limit myself to the par- .ticular construction and arrangement of parts shownanddcscribed, but aim, in the appended claims, to cover all modifications which are within the scope ofmy invention. What I claim as new and desire to secure by Letters Patent of the United States, is, I 1. A frequency indicator comprising relatively movable elementsone of said elements including two windings exerting opposing forces .on the other element, means for tuning the circuits of the two windings for two difierent frequencies, an indicator cooperating with said indicator.

.2. A frequency indicator comprising relatively movable elements, one of said ele.

ments including two windings exerting opposing forces on the other element, means for tuning the circuits of the two windings for two different frequencies, said two frequencies being respectively above and below the average frequency to be measured, an indicator actuated by the movable element, and a scale cooperating with said indicator.

3. A frequency indicator comprising relatively movable elements, one of said elements including two windings exerting opposing forces on the other element, means for tuning the circuits of the two'windings for two different frequencies, said two frequencies being respectively above and below the average frequency to be measured and differing therefrom by a small fraction of r the average 1 frequency, an indicator actuated by the movable element, and a scale 00- operating with said indicator. i

4. A frequency indicator comprising relatively movable elements, one of said elements including two windings exerting op-' posing forces on the other element, means for tuning the circuits of the two windings for different frequencies comprising a reactance and a condenser in series with each of said two windings, an indicator actuated by the movable element, and a scale cooperating with said indicator.

5. A frequency indicator comprising relatively movable elements, oneof said elements including two windings exerting opposingforces on the other element, a reactance and a condenser in series with each of said two windings, means for adjusting the relative amounts of said reactances and condensers, an indicator actuated by the movable element, and a scale cooperating with said indicator.

6. A frequency indicator comprising three windings, two of said windings being relatively fixed with regard to each other and relatively movable with respect to the third winding and arranged to.

, exert opposing forces on the third winding, means for tuning the circuits of the two relatively fixed windings for two different frequencies, and an indicator actuated by one of said windmgs.

7 A frequency indicator comprising relatively movable elements, one of said elements including two windings placed at an angle to each other and connected so as to exert opposing forces on the other element, means for tuning the circuits of the two windings for two different frequencies, an indicator actuated by the movable element, and'a scale cooperating with said indicator.

8. A frequency indicator comprising a stationary element and a movable element, said movable element including two windings exerting opposing forces on the stationary element, meansfor tuning the circuits of the two windings for two diderent frequencies, and indicating means actuated by the movable element.

9. A frequency indicator for indicating the frequency of an alternating current comprising relatively movable elements, one of said elements including two windings connected to the source of said alternating current and placed at an angle to each other and connected so as to exert opposing forces I ated by the movable element, and a scale cooperating with said indicatorfor indicating the frequency of said alternating current,

10. A frequency indicator for indicating the frequency of an alternating current com- I prising a stationary element and a movable element, said movable element comprising two coils placed at an angle to each other and connected in parallel with one another and in series with the static-nary element,

means for tuning the circuits of the two coils for different frequencies comprising a condenser in series with each coil of the movable element, and indicating means actuated by said moving element for indicating the frequency of said alternating current.

In witness whereof, I have hereunto set my hand this sixteenth day of September 1911.

WILLIAM H. PRATT.

Witnesses:

JOHN A. MCMANUS, Jr., WM. A. MAYOR. 

